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Talk about Adafruit Raspberry Pi® accessories! Please do not ask for Linux support, this is for Adafruit products only! For Raspberry Pi help please visit: http://www.raspberrypi.org/phpBB3/

I think we all agree that something is wrong. A WiFi dongle in normal operating conditions shouldn't be able to brew a mean cup of tea. The fact that the dongles work elsewhere isolates the problem to this specific RasPi.

My question is whether the voltage across the USB supply pins has gotten reversed, and the heat is a sign of input protection diodes pumping a lot more current than they really want to. That's peripheral to the question of whether the device is (pardon the term) toast though.

My vote is to swap that one for another and hoist the thing up on a tiny grease rack to see what's going on.

When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.

- The Pi works fine with a webcam plugged into the USB socket- The wifi dongle works fine when plugged into another device- Putting the wifi dongle in the Pi's USB socket makes the dongle heat up

You said you tried a powered hub. Again, to avoid tripping over the obvious, I take that to mean you plugged a powered hub into the Pi's USB port and plugged the webcam/wifi dongle into the hub. Webcam worked, wifi didn't.

If all those statements are correct, this is starting to sound like an integration problem (only shows up when you put things together).

When you void a product warranty, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.

I have the same device. I just got around to testing it with my pi today. If you put it in as the only usb item, the entire pi dies. If you take it out the pi works fine. If I try and use the dongle in my PC, Windows doesn't even show it in the device manager. Take the dongle out of the PC and it burns to the touch. I hope it's still useful for something.